Light metal thiocyanate derivatives of phosphor-sulfurized aliphatic hydrocarbons



Patented Aug. 31, 1954 LIGHT METAL THIOCYANATE DERIVATIVES OF PHOSPHOR-SULFURIZED ALIPHATIC HYDROCARBONS Joseph M. Hersh, Pennsauken, N. J., assignor to Continental Oil Company, Ponco City, Okla., a

corporation of Delaware No Drawing. Application November 4, 1950, Serial No. 194,196

2 Claims. (Cl. 260-139) 1 This application is a continuation in part of my copending application, Serial No. 609,809, filed August 9, 1945, now abandoned.

This invention relates to lubricant improvingv agents and improved lubricating compositions, and more particularly pertains to such compositions which are especially adapted to inhibit corrosion of lubricated parts and possess or impart stability towards oxidation of the oil, etc.

It is recognized that hydrocarbon materials reacted with a phosphorus sulfide result into products possessing acid characteristics, and that such materials when employed in plain lubricating oils serve to enhance the anti-sludging, anti-oxidant, corrosion inhibiting, etc. properties thereof. By reason of the acid characteristics of the phosphorus sulfide-hydrocarbon reaction product, it was heretofore found that a metallic reagent such as sodium sulfide could be reacted therewith to produce end products which are substantially enhanced in beneficial characteristics, such as imparting greater stability, etc. to lubricating oils. While these metal containing reaction products have been an improvement over the metal-free products, nevertheless, in view of modern day usage of copper and silver alloy bearings, there is still a great need for improvement in corrosion inhibiting characteristics of lubricants. Now, therefore, by means of the present invention a substantial improvement in corrosion inhibiting properties of lubricants is effected.

An object of this invention is to provide an addition agent which is especially adapted to inhibit corrosion of lubricated parts.

Another object is to provide improved lubrieating compositions.

Still another obj ect is to provide a novel method of preparing a corrosion inhibitor for lubricating oils. Other objects and advantages of this invention will become apparent from the following description thereof.

Essentially the present invention is concerned with a lubricant improving agent comprising an aliphatica hydrocarbon-phosphorus sulfide product reacted with a thiocyanate of a light metal. More particularly, this invention involves lubricating compositions comprising minor amounts of a material prepared by reacting an aliphatic hydrocarbon with a phosphorus sulfide and then reacting same with a light metal thiocyanate in combination with a lubricating oil.

The intermediate derivative of my invention is prepared by reacting an aliphatic hydrocarbon with a phosphorus sulfide. The aliphatic hydrocarbon is preferably unsaturated, although the saturated types can be used in preparing the intermediate derivative. In general, about 2 to 50 parts by weight of a phosphorus sulfide are reacted with about 100 parts of aliphatic hydrocarbon, preferably about 12 to 24 parts of a phosphorus sulfide with about 100 parts of aliphatic hydrocarbon, at a temperature of about 200 to 360 F., preferably 300 to 360 F., and for a period of about 0.25 to 1 0 hours, preferably about to 2 hours.

The aliphatic hydrocarbon is either saturated or unsaturated and includes for example, the following classes and specific compounds. Saturated straight or branched chain hydrocarbons, e. g., hexane, octane, iso-octane, decane, hexadecane, etc.; olefinic hydrocarbons e. g., 'octadecene, do-

decene, polymerized iso-butene, amylene, ethylene,

butadiene, melene, cetene, wax olefins, propylene polymers, amylene polymers, etc. While the olefinic hydrocarbon can be mono-, di-, tri-, etc., unsaturated, it is preferred to employ the monoenic olefin. The monoenic olefin can be represented by the formula CnHzn, or more specifically by the structure RCH=CH-R, wherein both Rs are alkyl groups, and the entire molecule comprises about 10 to carbon atoms. These monoenic olefins can be obtained from any source, however, those derived from halogenating and dehydrohalogenating petroleum fractions in accordance with the method described in my copending application, Serial No. 609,809, filed August 9, 1945 are preferred. In this respect it is to be noted that excellent results are obtained with a monoenic wax olefin having predominantly 18 to 24 carbon atoms, and which is obtained by halogenating and dehydrohalogenating a predominantly C1z';C24 petroleum wax fraction. Monoenic olefins having 10 to 60 carbon atoms are more desirable than heavier olefins because the intermediate derivatives formed therefrom tend to be readily oil soluble and easy to handle, whereas the heavier hydrocarbons yield products which are very viscous and relatively difficult to handle. Likewise, from the standpoint of solubility characteristics those hydrocarbons containing less than about 10 carbon atoms produce intermediate derivatives which are less desirable than those derived from the preferred hydrocarbon. Notwithstanding such differences 1. e. between the products derived from lighter and heavier hydrocarbons and those derived from the preferred C10-C60 monoenic olefin, it will be found that such lighter and heavier hydrocarbons are useful for the purposes of this invention.

The reaction between an aliphatic hydrocarbon and a phosphorus sulfide is well known, and it appears that the products obtained therefrom can contain varying amounts of phosphorus and fide is effected with greater facility and ease than when using a saturated hydrocarbon. Furthermore, for this invention, it is preferred to obtain intermediate products having as much phosphorus in chemical combination as is possible, since phosphorus imparts greater acid characteristics to the product and makes possible the inclusion of more metal in the end product.

The phophorus sulfide employed as the reagent in preparing the intermediate derivative should contain at least phosphorus and sulfur and have the property of imparting such elements into the intermediate derivative. Specific examples of such reagents are phosphorus disulfide, Pass (or PS2) phosphorus trisulfide, P4S6 (or P283) phosphorus sesquisulfide, P483; phosphorus pentasulfide, PzSs; phosphorus heptasulfide, P4S'1; etc.

The intermediate derivative described above is then reacted with a thiocyanate of a light metal in order to incorporate metal into the end product, and neutralize the acidic property thereof, either partially or wholly, or to excess alkalinity. The thiocyanate employed contains a light metal, such as the kind described in Hackhs dictionary, viz, those metals having a. density less than four. Included with the light metal thiocyanates are the alkali and alkaline earth metal thiocyanates. Specific examples of light metal thiocyanates are aluminum thiocyanate, barium thiocyanate, calcium thiocyanate, lithium thiocyanate, magnesium thiocyanate, potassium thiocyanate, sodium thiocyanate, strontium thiocyanate, etc.

It is to be understood, however, that not all the thiocyanates of light metals are equivalent for this invention, but that under certain conditions some are more effective or desirable than others.

The reaction between the light metal thiocyanate and the intermediate derivative is conducted at a temperature of about 150 to 400 F., preferably about 200 to 300 F. At this temperature, about 0.1 to 10 moles of the light metal thiocyanate, preferably 1 to 4 moles of same, are reacted with about 1 mole of the intermediate derivative. The total reaction time is in the order of about to about hours, preferably about to 2 hours. It is preferred to employ an inert gas atmosphere above the reaction mass. and for this purpose for example, nitrogen, CH4, etc. can be used. Usually, this inert gas atmosphere is maintained by the application of a small pressure in the order of up to about 25 to 30 p. s. i. g., and more usually about 10 to p. s. i. g.

The following specific examples will serve to illustrate the methods of preparing the intermediate derivative and the metal containing end products.

EXAMPLE I A wax hydrocarbon containing 18 to 24 carbon atoms was halogenated and dehydrohalogenated, in accordance with the method described in my copending application, Serial No. 609,809, filed August 9, 1945, to obtain a wax olefin having an iodine number of '72. 100 parts of the wax 01efin are heated to about 200 to 250 F. At this temperature a small portion of 21 parts by weight of P285 is added to the heated olefin so as to preclude any olefin polymerization and start the phospho-sulfurization reaction. The heating and stirring of the reaction mixture is continued with the addition of increments of P285 and the raising of the reaction temperature, until a temperature of about 340 to 360 F. is attained. The temperature is maintained at 350 F., plus or minus 10 F., and by means of stirring, all of the Pass has become completely solubilized. The reaction between the reactants is quite rapid, however, it is preferred to continue heating for another 30 minutes in order to insure complete reaction.

Another preferred aspect of this reaction is to keep an atmosphere of inert gas such as for example N2, CH4, etc. above the reaction mixture. This can be accomplished in the same manner as described hereinabove for the reaction with the thiocyanate.

EXAMPLE II One molal quantity of the product produced in Example I is diluted with an equal weight of diluent oil which contains about one part per thousand of silicone oil (an anti-foaming agent), and heated to 200 F. under a 10 p. s. i. g. atmosphere of nitrogen. One molal part of sodium thiocyanate dissolved in 15 cc. of boiling water is added at a temperature of about 200 to 250 F. The temperature is then raised to 300 F. and the water is substantially removed. The product is clarified by centrifuging and/or filtering. The oil solution of this additive is bright and clear.

In order to determine the eifectivenes of the products of the present invention, Underwood tests under conditions of accelerated corrosion, were carried out. In these tests the oil is subjected to the Underwood test plus the following accelerative conditions:

(1) Progressive addition of corrosion accelerator (soluble lead naphthenates) equivalent to 0.025% of lead as PbO every 2 /2 hours; and

(2) The injection of air over the hot oil bath at the rate of cu. ft. per minute.

In each of the tests reported below, the additive to be tested was added to an SAE 20 Mid- Continent refined oil plus 0.4% methyl dichlorstearate. Furthermore, in each of the tests, the additive to be tested was added in quantities totaling 1.25% based on the total composition, and the composition contained about 0.075% sulfur.

Table I Corrosion Loss Induction Time, Hours Cu-Pb, Hours Cd-Ag, Hours Cd-Ag Cu-Pb l0 15 20 l0 15 20 A. Product of Ex. I 14.0 12.0 0 0.2 1. 4 0 1.2 3.15 B. Product of Ex. II 13. 0 12.0 0 0.3 0.92 0 l. 0 2. 35 C. Past-wax olefinNazS* 14. 5 14.0 0 0. 1 1. 2 0 0. 25 2. 70 D. Past-Wax 01efin-NazS""-. 14.0 15.0 0 0. 2 1.2 0 0.15 2. E. Past-wax olefin-NazS.-. 14. 0 15.0 0 0. 1 0.9 O 0 1.83

Two moles of product of Ex. I reacted with 1 mole of Na1S in accordance with method of Ex. II.

"One mole of product of Ex. I reacted with 1 mole of Na1S in accordance with method of Ex. II.

From the above data it can be seen that the product obtained by reacting a thiocyanate with the intermediate derivative is substantially better than when using Nags in place of the thiocyanate in the same reaction. This is borne out by a comparison of tests B and D, wherein the same quantities of metallic reagents were employed, but the corrosion loss for the thiocyanate product was substantially less than the sulfide product. In the case of copper-lead alloy, the thiocyanate product is about as effective as the sulfide product, even though 50% more sulfide reagent is used than the thiocyanate.

It is contemplated for the purposes of this invention, to employ about 0.01 to 20% of the phosphorus sulfide-aliphatic hydrocarbon-light metal thiocyanate product in lubricating oils. For automotive oils, it is preferred employing about 0.5 to 4%, whereas for heavy duty oils about 1 to is preferred.

The lubricating oils which can be used as a base for the finished compositions include those of animal, vegetable, marine, mineral or synthetic origin. Generally, it will be found that the base oil will be of mineral origin due to the abundance and wide use of such oils. The lubricating oil can have a viscosity of 30 to 2000 SUS 100 F., although ordinarily the lubricating oil will have a viscosity of about the SAE 10 to 90 oils.

Having thus described my invention and provided specific examples thereof, it is to be understood that no undue limitations or restrictions are to be imposed by reason thereof, but that the scope of my invention is defined by the appended claims.

3 Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims or the equivalent of such be employed.

I therefore particularly point out and distinctly claim as my invention:

1. A new composition of matter comprising a product which is prepared by reacting about 2 to parts by weight of a phosphorus sulfide with about parts by weight of an aliphatic hydrocarbon at a temperature of about 200 to 360 F. for from about A to 10 hours, wherein said aliphatic hydrocarbon is a mixture of wax olefins having an average of 18 to 24 carbon atoms per molecule and an average of about 1 unsaturated linkage per molecule and then reacting same with a light metal thiocyanate at a temperature of about to 400 F.

2. A new composition of matter comprising a product which is prepared by reacting about 12 to 24 parts by weight of a phosphorus sulfide with about 100 parts by Weight of an aliphatic hydrocarbon at a temperature of about 300 to 360 F. for from about /2 to 2 hours, wherein said aliphatic hydrocarbon is a mixture of wax olefins having an average of 18 to 24 carbon atoms per molecule and an average of about 1 unsaturated linkage per molecule and then reacting about 1 mole of same'with about 0.1 to 10 moles of a light metal thiocyanate at a temperature of about 150 to 400 F.

References Cited in the file of this patent UNITED STATES PATENTS Hersh July 25, 1950 

1. A NEW COMPOSITION OF MATTER COMPRISING A PRODUCT WHICH IS PREPARED BY REACTING ABOUT 3 TO 50 PARTS BY WEIGHT OF A PHOSPHORUS SULFIDE WITH ABOUT 100 PARTS BY WEIGHT OF AN ALIPHATIC HYDROCARBON AT A TEMPERATURE OF ABOUT 200 TO 360* F. FOR FROM ABOUT 1/4 TO 10 HOURS, WHEREIN SAID ALIPHATIC HYDROCARBON IS A MIXTURE OF WAX OLEFINS HAVING AN AVERAGE OF 18 TO 24 CARBONS ATOMS PER MOLECULE AND AN AVERAGE OF ABOUT 1 UNSATURATED LINKAGE PER MOLECULE AND THEN REACTING SAME WITH A LIGHT METAL THIOCYANATE AT A TEMPERATURE OF ABOUT 150 TO 400* F. 